1. Field of Invention
This apparatus relates to a method of automatically controlling machines that supply solvents to and into internal combustion engines for the purpose of cleaning internal parts in those internal combustion engines.
2. Description of Prior Art
A problem common to internal combustion engines is the build-up of carbon and other organic compounds on the internal engine surfaces. If ignored this build-up of material causes parts to change in both shape and size. This change is considered more detrimental today because in addition to a loss of efficiency, air pollution is drastically increased. If left undeterred small orifices are closed off and eventually the engine ceases to operate.
This problem is particularly damaging to all types of fuel injectors. Today with increased awareness of air pollution caused by the inefficient burning of petroleum products it is important to keep injectors and their associated parts clean.
An early solution to this problem was to dismantle the engine and physically scrape or sandblast the deposits off the parts. Dismantling an engine and a fuel delivery system requires a relatively long down time and is very skilled-labor intensive. As a result it is a very expensive choice and, therefore not performed very often.
In order to reduce the time and money required to maintain the integrity of these components solvents were developed that would remove some of the deposits and make the remaining removal processes less labor intensive. U.S. Pat. Nos. 4,082,565 Sjolander (1978) and 4,804,005 Hartopp (1989) describes an apparatus used to chemically clean injectors which have been removed from an engine.
An improvement was the development of solvents which could be added to the engine fuel storage tank and allow the solvent to run through the engine with the fuel while the engine operated. This introduced a new problem because in many cases the solvents did not dissolve the deposits but rather released them. Some of the dislodged particles returned to the fuel tank, others moved to different parts of the engine. When free, these deposit particles could do more damage than when they were fixed on the engine parts.
A solution to this new problem was to feed the engine from a separate fuel and cleaning solvent mixing tank and discard any remaining fuel-cleaner mixture along with the released particles.
In order to overcome the problem of not completely dissolving the carbon and organic deposits new stronger solvents were formulated. These could be mixed with limited quantities of fuel in a mixing tank and circulated through the fuel system of the engine while it was operated.
Unfortunately these new superior cleaners are so corrosive that they cannot be added to the vehicles fuel storage tank because they will dissolve rubber and plastic hoses and damage some metal parts. This is a second substantial reason for using a separate fuel-solvent mixing tank.
The prior art improves this apparatus by adding pressure control devices, controls for operating the injectors, and a timing device that should allow the cleaning cycle to go on without the presence of the mechanic. Finally the whole apparatus is made portable by placing it on a wheeled dolly. This allows the described apparatus to be moved to the vehicle.
An apparatus embodying these features is described by U.S. Pat. Nos. 4,520,773 Koslow (1985), 4,606,311 Reyes et al (1986), 4,877,043 Carmichael (1989),. The apparatus described in these above mentioned patents require that the operator be specifically trained to operate the equipment. There are toggle switches and gauges which must be set. Previously described apparatus require the operator monitor the pressures throughout the service to insure proper operation.
Previously described apparatus require the pump motor to operate at full capacity. Pressure control is accomplished by bypassing excessive flow and pressure back to the mixture tank. This causes the pump motor to become excessively heated. In addition the fuel-cleaner mixture is also heated by the operating engine which adds more heat to the pump motor.
Previously described apparatus require a series of switches and relays to operate the solenoid valves and pump motor. These components are prone to failure due to their electro-mechanical nature.
Another limitation to the previously described apparatus is that the user must make many hand adjustments to set up the apparatus and through out the cleaning cycle.
Another limitation of the previously described apparatus is fuel-cleaner mixture supply pressures are controlled by setting various mechanical devices. The resultant pressure is prone to variation from dirt particles, changes in temperature or the addition of cleaning solvent to the fuel. Changes in engine speed or rate of fuel consumption as the injectors open up also change fuel pressure. In using the described apparatus the operator should make a hand adjustment of fuel pressure controls repeatedly as each of these changes occur.
Prior art does not consider the ramifications of a possible leak of the hot fuel-cleaner mixture occurring internal to the apparatus. The hot fuel would begin to vaporize since it was no longer under pressurization. This would create an explosive environment. The closing or opening of an electro-mechanical switch could cause a spark which would ignite the vapors.
A continuous uninterrupted source of fuel is essential for the operation of diesel engines. If a diesel engine is allowed to run out of fuel air will enter the fuel lines and thus the fuel injection system. It is a time consuming inconvenience to re-prime the fuel injection system and remove all the air from the injection system in order to get the engine started again. The prior art does not describe a safeguard to prevent the diesel engine from running out of fuel.
The previously described apparatus employ mechanical gauges and pressure regulators, relays, solenoid valves and switches. U.S. Pat. No. 4,787,348 Taylor (1988) describes an apparatus that uses pressure sensing probes sending electrical signals to relays and the relays control solenoid valves which effect the required changes in the system. Unfortunately, the described apparatus are exceedingly complicated. Taylor's diagram, sheet 3 of his application, shows two 3 way solenoid valves, three relays, six electro-mechanical switches, many components and about 60 electrical connections.
In use, the previously described apparatus is wheeled outside on a dolly to attach to a vehicle. The combination of mechanical jarring, sub-zero weather conditions and dampness leads to frequent mechanical failure of one or more components. When the described apparatus fails, it may stop operating, but it may also leave a fuel line open to an operating engine which can lead to destruction of the engine or a serious fire hazard.
When the previously described apparatus is attached to an engine there is no way to know if it is operating properly. The user is left to hook it up and only when it fails is he alerted to the fact that he has a malfunction.
Another limitation of the Taylor apparatus is that there is no means for adjusting the pressure of the fuel-cleaner mixture that is fed to the diesel engine. This is a real problem in the field since diesel engines require pressures of 1 to 12 PSI. If the pressure is exceeded the inlet seals of the injector pump on the engine will begin to leak.
Another limitation of the previously described apparatus is that they only operate at one voltage with the exception of the Taylor apparatus which also operates on 115 volts of alternating current. In practice alternating current is not available where these engines are located. Engines have electrical systems which operate at many different voltages and it is convenient to be able to operate the apparatus by drawing power from the engines electrical system, no matter what the operating voltage. More serious, if for some reason the supplied voltage is out of the operating range of the described apparatus and the user attaches it anyway, the described apparatus could be destroyed or seriously damaged.